Tensor format: .tco

[fredrikbk]

We want to support a custom taco file format .tco. These files should contain ascii text as follows:

• An optional header preceded by ##taco , containing one of float double uint32_t ...
• One or more comment lines at the beginning preceded by #
• A line with the dimension sizes for each order
• A line with the dimension storage types
• A line with the dimension storage order (for each dimension, which tree level it is stored at)
• For each (permuted) storage dimension, one line of values per index (no indices for dense types)
• A line with values array

Example:

##taco double
# comment
4 4 7 5
d s s d
0 1 3 2
0 2 3 3 5
0 1 1 2 3
0 1 1 3 4 7
0 1 1 2 3 4 6
0.1 1.2 2.0 3.4 4.0 5.6 2.0